hi:  this should be a simple one:
a sci fi on nutron star where a starship that orbits around a nutron
star beams down encyclopedia to help its primitive life forms (small,
flat jelly-like beings whose time-scale is one millionth of us(ie 1
million times faster than us)).  by the time it's beaming "z", the
lifeforms already developed inter-stellar flight and turned around and
helped Earth averting cataclysm by eliminating local disturbances in
the core of Sun.

I believe you are thinking of the 1980 novel "Dragon's Egg," by the
late Robert L. Forward.

Here is an excerpt from a review of the book:

"What if there were intelligent creatures on the surface of a neutron
star, one that's twenty kilometers in diameter with a surface
gravitation 67 billion times that of the earth? Forward thinks
through, in great detail, what such creatures and their history and
civilization might be like, and he tells a good story about the cheela
(as they are called) and their interactions with some human
explorers--interactions complicated by cheelas' and humans' vastly
different experiences of time. The book includes an illustrated
"technical appendix" about the neutron star, the cheela, and the human
spaceship (information extracted from the 2064 edition of a science
encyclopedia published by Random House Interplanetary)."

Amazon.com
http://www.amazon.com/exec/obidos/tg/detail/-/034543529X/qid=1037040679/sr=8-1/ref=sr_8_1/102-3781554-8305755?v=glance&s=books&n=507846

Here you will find a few more descriptions of plot details:

David Darling's Astrobiology Central
http://www.angelfire.com/on2/daviddarling/Dragons.htm

ReadLiterature.com
http://www.readliterature.com/TL-37.htm

Newgroup post
http://groups.google.com/groups?selm=7ioq7k%244s7%40sjx-ixn10.ix.netcom.com&oe=UTF-8&output=gplain

My search strategy was greatly simplified by the fact that I
recognized the plot of "Dragon's Egg" from your description. To find
online references, I used these search keywords:

Google Web Search: "dragon's egg" + "robert l forward"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22dragon%27s+egg%22+%22robert+l+forward

Google Groups Search: "dragon's egg" + "robert l forward"
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22dragon%27s+egg%22+%22robert+l+forward%22&sa=N&tab=wg

If you enjoyed "Dragon's Egg," be sure to read "Starquake," its
sequel:

Amazon.com
http://www.amazon.com/exec/obidos/tg/detail/-/0595167489/qid=1037042164/sr=8-4/ref=sr_8_4/102-3781554-8305755?v=glance&s=books&n=507846

Thanks for asking a question about one of my favorite works of science
fiction! If, by any chance, this was not the book you were thinking
of, please request clarification before rating my answer, and I will
gladly resume the search.

Best wishes,
pinkfreud

right on target - thank you for the answer, hey maybe you can help me
with my other science fiction query???  thanks again!

As usual, a perfect answer from pinkfreud-ga, one of our very best
researchers in my opinion.

 [Personally, I think it's a 5-star answer - I guess I'm lucky I
didn't get the lock though!]